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    <script>
        // const 常量名 = 值;

        const TEST = "测试";
        console.log(TEST);
        /* 
            常量的使用规范
            - 命名尽量要大写
            - 声明了常量必须赋值
            - 常量的值是不能修改的
        */

        // const TEST1; //SyntaxError: Missing initializer in const declaration  缺少初始值

        // TEST = "哈哈";  //TypeError: Assignment to constant variable.  不能重新赋值给常量
        
        const PI = Math.PI;
    </script>
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